linux/arch
Kamalesh Babulal e36a82ee4c powerpc/livepatch: Fix livepatch stack access
While running stress test with livepatch module loaded, kernel bug was
triggered.

  cpu 0x5: Vector: 400 (Instruction Access) at [c0000000eb9d3b60]
  5:mon> t
  [c0000000eb9d3de0] c0000000eb9d3e30 (unreliable)
  [c0000000eb9d3e30] c000000000008ab4 hardware_interrupt_common+0x114/0x120
   --- Exception: 501 (Hardware Interrupt) at c000000000053040 livepatch_handler+0x4c/0x74
  [c0000000eb9d4120] 0000000057ac6e9d (unreliable)
  [d0000000089d9f78] 2e0965747962382e
  SP (965747962342e09) is in userspace

When an interrupt occurs during the livepatch_handler execution, it's
possible for the livepatch_stack and/or thread_info to be corrupted.
eg:

  Task A                        Interrupt Handler
  =========                     =================
  livepatch_handler:
  mr r0, r1
  ld r1, TI_livepatch_sp(r12)
                                hardware_interrupt_common:
                                  do_IRQ+0x8:
                                    mflr    r0          <- saved stack pointer is overwritten
                                    bl      _mcount
                                    ...
                                    std     r27,-40(r1) <- overwrite of thread_info()

  lis r2, STACK_END_MAGIC@h
  ori r2, r2, STACK_END_MAGIC@l
  ld  r12, -8(r1)

Fix the corruption by using r11 register for livepatch stack
manipulation, instead of shuffling task stack and livepatch stack into
r1 register. Using r11 register also avoids disabling/enabling irq's
while setting up the livepatch stack.

Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Reviewed-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Reviewed-by: Balbir Singh <bsingharora@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
2017-10-10 15:27:42 +11:00
..
alpha Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
arc arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
arm arm/syscalls: Optimize address limit check 2017-09-17 19:45:33 +02:00
arm64 Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-24 11:53:13 -07:00
blackfin Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
c6x arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
cris MTD changes for 4.14: 2017-09-09 14:48:21 -07:00
frv arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
h8300 arch: define CPU_BIG_ENDIAN for all fixed big endian archs 2017-09-08 18:26:48 -07:00
hexagon Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-04 11:52:29 -07:00
ia64 Merge branch 'work.ipc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-09-14 17:37:26 -07:00
m32r arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
m68k Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/gerg/m68knommu 2017-09-10 21:07:39 -07:00
metag arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
microblaze Merge branch 'akpm' (patches from Andrew) 2017-09-09 10:30:07 -07:00
mips pci-v4.14-fixes-2 2017-09-22 13:09:11 -10:00
mn10300 arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
nios2 nios2 update for v4.14-rc1 2017-09-15 12:47:21 -07:00
openrisc OpenRISC patches for 4.14 2017-09-13 11:52:18 -07:00
parisc parisc: Unbreak bootloader due to gcc-7 optimizations 2017-09-22 22:26:43 +02:00
powerpc powerpc/livepatch: Fix livepatch stack access 2017-10-10 15:27:42 +11:00
s390 s390/topology: enable / disable topology dynamically 2017-09-20 13:47:55 +02:00
score Merge branch 'uaccess.strlen' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-07-06 22:07:44 -07:00
sh arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
sparc Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2017-09-11 18:34:47 -07:00
tile Merge git://git.kernel.org/pub/scm/linux/kernel/git/cmetcalf/linux-tile 2017-09-22 13:02:54 -10:00
um arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
unicore32 unicore32/PCI: Replace pci_fixup_irqs() call with host bridge IRQ mapping hooks 2017-08-03 16:29:34 -05:00
x86 Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-09-24 12:33:58 -07:00
xtensa arch: remove unused *_segments() macros/functions 2017-09-22 12:59:52 -10:00
.gitignore
Kconfig - For the randstruct plugin, enable automatic randomization of structures 2017-09-07 20:30:19 -07:00